Hydraulic control mechanism



Aug. 7, 1945. w. F. WILLI-:TTv I 2,381,795 I HYDRAULIC CONTROL MECHANISMFiled Feb. 14, 1941 4 Sheets-Sheet 2 Aug. 7, 1945. w. wlLLETT 2,381,795

HYDRAULI C CON TROL ME CHANI SM Filed Feb. 14, 1941 4 Sheets-Sheet 3Aug. 7, 1945, w. P. WILLETT 2,381,795

- HYDRAULIC CONTROL MECHANISM A Filed Feb. 14, 1941 4 sheets-sheet 4 vINVENTOR.

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Patented Aug. 7, 1945 wonen P. wine, 'raam ruk,

Hd., signor corporsted, Detroit, Mich.; a corhigan to Vickers, Inporation o! Mic Application February 14, 1941, Serial No. 378,920

ummm. (otto-ss) 'This invention relates to a hydraulic controlmechanism.

It is an objectY of the presentinvention to provide a control mechanismfor a hydraulic circuit in which movement is started by the shifting ofa hand lever and stopped automatically by a control mechanism at apredetermined point in the movement of the device being controlled. Theinvention contemplates a servo-*control used incombination with thecontrol device so that the speed of the member being controlled may beregulated by the operato Another feature of the invention has to dowith-an automatic means for venting the operating lines at thecompletion of a cycle thereby obviating any tendency for the outputshaft to creep. due to imperfect centering of the variable displacementpump which is used in the system.

' A further object of the invention is to provide a hydraulic circuitwhich may be stopped,

started, or reversed at any point in the cycle of the operation.Provision is also made for the operation of the control elements by handin the event that there'is pressure failure in the servocontrolmechanism.

Other objects and features of the invention relating to details of thecircuit and operating means therefor, will be apparent in the followingdescription and claims.

In the drawings:

Fig. 1 illustrates the circuit of the present invention'with the partsin the position which follows the reversal movement after the hand leverhas been moved back to neutral.

Fig. 1A is a side view of the brake mechanism shown in Fig. 1.

Fig. 2 shows the circuit with the parts as they would be positioned nearthe beginning of a forward movement but after the pump has been advancedto its full volume position by the control mechanism.

Fig. 3 shows the circuit at the end of the iorward movement before thehand lever has been returned to neutral.

Fig.`4 shows the circuit with the parts in their position near thebezinning of a reversing movement but after the pump has been advancedto its full volume position by the control mecha- I'he system as shownis particularly adapted tovarious typesofmachinery butisespecially'suitable for drivingordnance equipment such as ammunition hoists andremmers. The circuit shown is particularly adapted for a rammer andv uwm be desonbed in connection with o, ramming movement and a retractinsmovement. al-

though the rammer mechanism is not shown.

The main elements of the circuit include an electric motor' Il whichdrives a reversible variable pump II. The pump H furnishes liquid underpressure to a hydraulic motor I2 which has an operating shaft il. Abraking wheel Il is mounted on shaft Il and a brake shoe II is connectedto a bellcrank Il operated by 'a piston H.

` The elengents o! the control for the hydraulic circuit include ilrst,a movable member 2l on pump il which controls the rate and direction ofilow through the pump according to its displacement from center. A valve2| operated by a hand lever 22 controls the position of a piston 23which actuates the movable memberll. Hand lever 22 has a ram position asshown and a rego tracted position.` -A rod 24 and a spring 2i connectthe hand lever with a lever 2l which is connected at one end to themember 2l and the other end to a link 21 and rod :l leading to the valve2|. A piston rod 2l on piston 2l is con- 25 nectedv to the other end oflever 2B and also is 3o threadV back 35 timing valves 31 40 duits 4sonoas. conduit u 4l duits 41 and' 4l. Valve connected to a lever Itwhich serves as part of an automatic control for decelerating and stop.ping the motor l2.

Lever Il is operatedby nuts Il and 32 which and forth driven by powershaft il through bevel gears. The nuts Il and 32 are notched and slideon a bar Il to prevent their turning. Rod I3 also has cams 35 and Itwhich actuate. respectively, and ll in a housing Il. A valve 4i inhousing 42 is also arranged to be actuated bytbenuts liandninamannerwhich willbe described in detail.

Pump Il is connected to motor I2 by two conwill be under pressure duringthe ramming stroke while conduit 4i will be under pressure during theretraction stroke. These conduits are connected to the respective endsof the bore in housing 42 by conis so arranged that when either conduit4I or Il is underpressure. valve 4i will be shifted by the pressurewhich passesto the valve housing through conduits l1 and I port IIIbeing connected byaconduittl tovalvelandaporti! being connected by aconduit Il to valve-ll. A center port Il is'connected to a conduit It.Conduit which may be known as a bypass conduit, passesthrough arestricted portion l1 oi' valve 0n a threaded rod Il' Valve ll isconnected up hydraulically with valves l1 and Il, a

2| and the valve is properly positioned to a bypass valve 58 which iscontrolled by a cam 59 on rod 29. Conduit 56 is also connected to springpressed piston |1 of the brake mechanism by a conduit 60 so that whenthe bypass conduit is blocked by either valve 2| or 58, pressure willbuild up in the system and release the brake. With the bypass linevented throhgh both valves 2| and 58 as shown in Fig. 1, a spring 6|acting on piston |1 will engage the brake. Conduits 65 and 66 connectrespectively, the pressure conduits 45 and 46 with the bypass conduit 56through check valves 61 and 68.

At the left end of valve 2| a restriction 18 forms a valve whichcontrols conduits 11 and 18 which are connected respectively, withvalves 31 and 38. A pilot pump 88, driven by motor |8, directs pressurethrough pilot line 8| to valve 2| 'where it may pass a restriction 82 or83 to conduits 84 or 85 respectively, leading to the opposite sides ofpiston 23. A branch conduit 86 leads to a spring pressed valve 81 whichis normally held in the position shown by pilot pressure. In the eventof failure of pilot pressure, valve 81 shifts to the left to bypasslines 84 and 85. A relief valve 88 controls the pilot pressure whilevalves 98 and 9| connect the pilot line 8| respectively, with lines 45and 45 of the main circuit. Restrictions 92 and 93, leading to checkvalves 88 and 8| prevent the diversion of the entire flow of the pilotpump to the main circuity when the main circuit is vented.

In the operation, Fig. 1 illustrates the parts at the end of a reversemovement with the manual lever 22 in neutral position. To initiate a ramor forward movement, the lever 22 is moved ahead, as shown in Figs. 2and 3. The position of lever 26 at the beginning of the movement isshown in Fig. 3 wherein the valve 2| is shifted so that pilot pressurefrom line 8| may pass to.

line 85 and shift piston 23 to the left. During the initial movement oflever 26 it has pivoted at its lower end on the link connected to member28. As the piston 23 starts to move to the left, lever 26 will pivotabout its center mounting thereby returning valve 2| to neutral.Consequently, the piston 23 will move in a follow-up manner in a degreeproportional to the displacement of the lever 22 toward the ram positionbut at the end of the movement of piston 23, the valve 2| will be inneutral position, as shown in Fig. 1. The pump will then deliver to themotor at the capacity at which it is set as shown in Fig. 2 until nut 32engages lever 38 to move it from its Fig. 2 position to its Fig. 3position. In the movement of the piston 23 to the left, cam 59 isshifted to the left thereby permitting the valve 58 to drop and closeconduit 56 from the tank. Meanwhile, pressure is building up in conduit45 due to the displacement of the movable member 28. This pressure willreact through conduit 41 to shift valve 4| to its extreme rightposition. The shifting of valve 2| to the left will also block the ventin conduit 56, thereby causing pilot pressure to be built up abovepiston |1 to release the brake shoe I5. After motion has started, cam 58will have moved to the left where it allows valve 58 to close andmaintain the blocking of the vent in conduit 58. In this manner thesubsequent shifting of valve 2| is rendered ineffective as a means ofengaging the brake until the recentering of pump 28 has returned cam 58toopen the valve 58. The shifting of valve 4| to the position shown inFig. 2, blocks the center port 55 and thereby prevents bypassing of line55 through either of the valves i 31 or 38. As the forward movementprogresses, nuts 3| and 32 will shift to the left. Near the end of thecycle, nut 32 will contact the lower end of lever 38 and move the piston23 and movable member 28 gradually back to neutral position. Thisposition is shown in Fig. 3. Since the spring 25 is provided in rod 24,there will be a force on lever 25 which will shift valve 2| to the leftagain, as shown in Fig. 3 (provided the control lever is manually heldin the Ram" position shown). Liquid to the right of piston 23 will thusbe forced into lines 35 and 3| with check valve 33 taking care of volumedisplacement. Pressure from line 3| can not shift piston 23 since it isblocked by the nut 32. In the event the control lever is released duringthe deceleration and stopping action, it will follow the movement ofpump 28 to neutral. Nut 3| in traveling to the left, will shift valve 4|slightly to the left to open center port 55 to port 52 in line 53. Afterthis opening, when cam 35 reaches the point where valve 33 is open. asshown in F18. 3. the pressure in bypass line 53 will be transferredthrough line 13 to the tank around the restriction 13 in valve 2|. Thispath is shown in Fig. 3. Bypassing of line 55, of course. relievespressure on the piston |1 and applies the brake. It also relieves anypressure that might remain in lines 45 or 43 due to imperfect centeringof the member 28. There will, therefore, be no further movement of theshaft I3.

To effect reversal or retraction, the members are shifted as shown inFig. 4 with valve 2| being moved first to the right where it will admitliquid from line 8|, to the left hand end of the piston 23 and shift itto the right, after which, due to movement of the piston, the valve 2|will be re-centered. During the retraction movement valve 4| is in theextreme left position blocking the center port until at the end of themovement, as shown in Fig. 1, the nut 32 shifts the valve to open thecenter port to port 53 and valve 31 which will bypass line 55 to line 11and the tank, thereby stopping the system. At the end of the reversal,the nut 3| will shift the lever 38 back to its upright position, asshown in Fig. 1.

1. In a hydraulic variable speed transmission system for driving a loaddevice, a variable speed transmissing including a pump member and amotor member, a pressure responsive movable part on one of said membersfor varying the output speed and the direction of the transmission,lines connecting said pump member and motor member, each adapted toserve alternately as pressure and return lines, control means for themovement of said transmission comprising a manual control member,hydraulic means responsive to movement to said member for shifting saidmovable part to a position whereby pressure is directed through saidtransmission, andl means responsive to a predetermined movement of saidmotor lfor shifting said movable part gradually back to a neutralposition independently of said hydraulic means.

2. In a hydraulic mechanism, a reversible variable delivery pump with amovable control head for volume and directional control, a. reversiblemotor to be driven by pressure from said pump, lines connecting saidpump and motor, each adapted to serve alternately as pressure and returnlines, control means for the movement of said motor comprising a manualcontrol mem assnvos 3 ber havingneutral and actuating positions,hydraulic means responsive to movement oi' said member for sluiting saidpump control head to a position whereby pressure is directed to saidmotor, means responsive to la predetermined movement 'ot said motor.i'or sluiting saidhead gradually -back to a neutral positionindependentlv of said hydraulic means, means responsive to said motormovement to bypass said lines after s predetermined movement Vto preventfurther trol member remains in actuatins position, and additional meansVfor bypassing said lines when said control member is in neutralposition.

3. In a hydraulic mechanism, a reversible variicr volume control. areversible motor to be driven by pressure from said pump, linesconnecting said pump and motor, each adapted to serve alternately aspressure. and return lilies,v control means for the movement ci saidmotor comprising a manual control member, yhydraulic;means responsive tomovement of said member iorshittingsaid pump control headto'a positionwhereby pressure is directed to said motor, means rasive to said motormovement to bypass said lines to 'prevent further movement Y of saidmotor, 'said additional means being responsive to pressure in one or theother of said lines and arranged to be reset by said pressure attireVstart oi'va cycle oi' movement of said motor.

4. In a hydraulic mechanism, a reversible variable delivery pump with' amovable control head for volume control, vc. reversible motor to'bedriven by pressure from said pump, lines connecting said pump and'motor, each adapted'A to serve` alternately as pressure and returnlines,.co ntrcl means for thev movement of said motor comprising amanuall control member, hydraulic meansv responsive to movement oi' saidmember for shitting said pump control head to a positionwhereby pressureis directed to said motor, means responsive to a predetermined movementof said motor'iorv shifting said head gradually back to a neutral'position comprising a rotating shaft driven by said motorpnuts on saidshalt. means for holding said nuts against rotation but permitting axialmovement relative to the shaft, a lever to be actuated by one or theother ci said nuts, and means connecting said lever and lsaid controlhead whereby upon predetermined movement of said motor, said controlheadwill be moved back to a neutral position.

5. In a hydraulic mechanism, a reversible variable delivery plump with amovable control head for volume control, a reversible motor to be drivenby pressure from said pump. lines connecting said pump and motor, eachadapted to serve alternately as pressure and return lines, control meansfor the movement of said motor comprising a manual control member,hydraulic means responsive to movement of said member for shifting saidis directed to said motor, means responsive to a predetermined movementof said motor for shiftby one or the other of. said nuts, meansconnecting said lever and said control head whereby 7s shaft driven bysaid motor, nuts on said shaft,

, 65 said um and motor, each pump control head to a position wherebypressure p p l further movement oi' said motor.

6. In a hydraulic mechanism, a reversible-variable delivery pump with amovable control head l for volume control, a reversible motorl to bedriven by pressureirom said pump, lines ccn-d 10 necting said pump andmoton'each adapted to movement of said motor when said manual conservealternately as pressure and return! lines, control means tor themovement ot said motor comprising a manual control member, hydraulicmeans responsive to movement of said member lil for shifting said pumpcontrol head to a position able delivery pump with a movable controlhead 20 driven by said motor, nuts on said shaft, means for holding saidnuts against rotation but permitting axial movement relative to theshaft, a lever to be actuated by one or the other of'said nuts, meansconnecting said lever and said conv V "2B trol headwherebyuponpredetermined movement sponsive to a predetermined movementoi-s aid Y motor for shifting' saidhead. gradually hack to a neutralposition, and additional means'respona lo motor, said additional meansbeing responsive to pressure in one or the other oi' said lines andarranged to be reset by said pressure at the start lroi' a cycle ofmovement of said motor.

A '1. In a hydraulic mechanism, a reversible vini--vv 88 iable deliverypump with a. movable control head for Evolume control, a yreversiblemotor to be driven: by pressure'irom said'pump, lines connecting saidpump and motor, each adapted to ,serve alternately as pressure andreturn lines,

' t0 means for the movement oisaidV motor comprising a manual controlmember, hydraulic means responsive to movement of said member forshitting said pump control-head `to a position whereby pressure" is`directed to said motor,

45 means responsive to a predetermined movement ci! said motor forshitting said head gradually back to a neutral position, additionalmeans responsive to said motor movement to bypass said es to preventfurther movement oi' said motor,

5.0 comprising conduits connecting said lines and a series oi' valves insaid conduits including a. slow moving valve actuated by said motor anda fast moving valveactuated by said motor. and means connecting saidvalves and said motor whereby, 55 upon a predetermined movement of saidmotor,

said slow valve will have shifted to open said bypass lines and, at apredetermined point in the rotation oi said motor, said fast valvewillalso be moved to open said bypass lines thereby so preventingfurther movement of said motor.

8. In ahydraulic mechanism, a reversible variable delivery pump with amovable control head for volume control, a reversible motor to be drivenby pressure from said pum adapted to serve alternately as pressure andreturn lines, control means for the movement of said motor comprising amanual control member, hydraulic means responsive to movement'` of saidmember for 70, shit-ting said pump control head to a position wherebypressure is directed to said motor,

means responsive to a predetermined movement I of said motor forshifting said head gradually back to a neutral position comprising arotating lines connectingmeans for holding said nuts against rotationbut permitting axial movement relative to the shaft,

a lever to be ac-tuated by one or the other of said nuts, meansconnecting said lever and said control head whereby upon predeterminedmovement of said motor, said control head will be moved ba'ck to aneutral position, additional means responsive to said motor movement tobypass said lines to prevent further movemen-t of said motor, comprisingconduits connecting said lines and a series of valves-in said conduitsincluding a slow moving valve actuated by said motor and a fast movingvalve actuated bysaid motor, and means connecting said valves and saidmotor whereby, upon. a predetermined movement of said motor, said slowvalve will have shifted to open said bypass lines and, at apredetermined point in the rotation of said motor, said fast valve willalso be moved to open said bypass lines, thereby preventing furthermovement of said motor.

9. In a hydraulic mechanism, a reversible variable delivery pump with a'movable control head for volume control, a reversible motor to be drivenby pressure from said pump, lines connecting said pump and motor, eachadapted to serve alternately as pressure and return lines. control meansfor the movement of said motor comprising a manual control member,hydraulic means responsive to movement of said member for shifting saidpump control head to a position whereby pressure is directed to saidmotor, means responsive to a predetermined movement of said motor forshifting said head gradually back to a neutral position comprising arotating shaft driven by said motor, nuts on said shaft, means forholding sa.id`\nuts against rotation butv permi-tting axial movementrelative to the shaft/a lever to be actuated by one or the other of saidnuts, means connecting said lever and said control head whereby uponpredetermined movement of said motor, said control head will be movedback to a neutral position, additional means responsive to said motormovement to bypass said lines to prevent further movement of said motor,comprising conduits connecting said lines and a series of valves in saidconduits including a slow moving valve actuated by said motor and a fastmoving valve actuated by said motor, and means connecting said valvesand said motor whereby, upon a predetermined movement of said motor,said slow valve will have shifted to open said bypass lines and, at apredetermined point in the rotation of said motor, said fast valve willalso be moved to open said bypass lines, thereby preventing furthermovement of said motor, said slow valve being responsive to pressure inone or the other of said lines and being reset by said pressure at thestart of a cycle of movement of said motor.

10. In a hydraulic mechanism, a reversible variable delivery pump with amovable control head for volume control, a reversible motor to be drivenby pressure from said pump, lines connecting said pump and motor, eachadapted to serve alternately as pressure and return lines, control meansfor the movement of said motor comprising a manual control member,hydraulic means responsive to movement of said member for shifting saidpump control head to a position whereby pressure is directed to saidmotor, means responsive to a predetermined movement of said motor forshifting of said head gradually back to a neutral position, additionalmeans responsive to said motor movement to bypass said lines to preventfurther movement oi' said motor, comprising conduits connecting saidlines and a series of valves in said conduits including a slow movingvalve actuated by said motor and a fast moving valve actuated by saidmotor, and means connecting said valves and said motor whereby, upon apredetermined movement of said motor, said slow valve will have shiftedto open said bypass lines and. at a predetermined point in the rotationof said motor, said fast valve will also be moved to open said bypasslines thereby preventing further movement of said motor, said slow valvebeing responsive to pressure in one or the other of said -lines andbeing reset by said pressure at the start of a cycle of movement oi saidmotor.

Y WARREN P. WIILETI.

